1. Field of the Invention
This invention relates generally to a surgical instrument and its assembly and more particularly concerns a surgical instrument used for removing vitreous from the eye during intraocular surgery.
2. Brief Description of the Prior Art
An eye surgery operation performed behind the lens is called vitreous surgery, inasmuch as the back part of the eye is filled with a clear material called vitreous. If the vitreous is damaged it must be completely removed before eye repairs can be made. When the vitreous is removed, the body quickly replaces it with a substitute clear liquid.
A surgical instrument used in vitreous surgery typically is a small, hand-held probe which is inserted into the eye through an incision, and which includes a tube which draws in the vitreous material, and a cutting means which severs the material, allowing it to be drawn out through the tube by suction.
Instruments now used in vitreous surgery generally consist of a concentric arrangement of an inner tube driven by an air powered diaphragm inside an outer tube, with the outer tube extending distally beyond the inner tube. The outer tube has a side facing opening adjacent to its distal tip. When suction is applied to the inner tube, the vitreous is moved into the side facing opening of the outer tube. When the inner tube is then pushed axially forward by the air powered diaphragm, it shears off the vitreous material projecting through the hole in the outer tube. The vitreous material is then aspirated through the inner tube by an external suction source.
This conventional construction has several disadvantages. The axial cutting motion of a diaphragm driven probe creates vibration in an axial direction due to the relatively large mass of the inner tube filled with liquid and the flexible suction tubing attached to the inner tube. This creates a danger of damage to the retina or other structures of the eye. The axial vibrations increase as practical cutting speed is approached because of the movement of the diaphragm and the inner tube.
Conventional air diaphragm driven vitreous cutter probes have other limitations as well. The cutting speed of such probes is limited by the axial vibration of the instrument. The power of the air driven diaphragm is also limited by the use of a return spring and the limited size of the diaphragm which is determined by the size of the instrument probe itself. The flexible tubing connected to the inner tube in the conventional air driven diaphragm construction of these surgical probes also tends to transmit dangerous vibrational motion to the instrument if the tubing is touched during the surgical procedure.
The general object of this invention is therefore to overcome these disadvantages and limitations by providing an improved vitreous cutting probe for use in removing vitreous from the eye during ophthalmic surgery.
A related object is to provide such a surgical probe which has relatively few parts, is simple in design, and is inexpensive to manufacture.
A more specific object of the invention is to overcome the safety and performance limitations of a probe employing the conventional axially-reciprocating, air-driven diaphragm vitreous cutter probes.
Another object of the current invention is to increase the cutting speed of the surgical probe.
A still further object of this invention is to provide a cutting device with an inner cutting needle capable of high precision cutting.
A related object is to simultaneously reduce vibration while increasing the cutting speed of the instrument.
It is a further object of the invention to provide a simple and effective means to isolate the moving inner tube from the external suction means and the stationary outer tube of the surgical probe.
Other objects and advantages of the present invention will be apparent to those skilled in this art from the following description and the appended claims.